CT is definitely more harmful compared to ultrasound, because CT uses radiation to tomography the human body, so there is a certain amount of radiation to the human body, especially enhanced CT or more sequential examinations, then it will be more radiation to the human body. Pregnant women and some small children are generally not recommended to do it. Ultrasound uses ultrasound to sweep the body, which does not cause any harm to the body. Even so, it is not possible to decide which test to do according to the size of the damage to the human body, because CT and color ultrasound have different indications for human body examination, for example, lung diseases must be examined by CT, because ultrasound cannot pass through normal lung tissue, so it is also impossible to examine the lungs, while the skeletal system must also be examined by CT.